Grammar. a word, phrase, or clause, usually a substantive, that is replaced by a pronoun or other substitute later, or occasionally earlier, in the same or in another, usually subsequent, sentence. In Jane lost a glove and she can't find it, Jane is the antecedent of she and glove is the antecedent of it.

5.

Mathematics.

the first term of a ratio; the first or third term of a proportion.

the first of two vectors in a dyad.

6.

Logic. the conditional element in a proposition, as “Caesar conquered Gaul,” in “If Caesar conquered Gaul, he was a great general.”.

(logic) denying the antecedent, the fallacy of inferring the falsehood of the consequent of a conditional statement, given the truth of the conditional and the falsehood of its antecedent, as if there are five of them, there are more than four: there are not five, so there are not more than four